Weighing material on a conveyor

ABSTRACT

A weighing system for measuring the weight of a material carried on a conveyor assembly. The weighing system is compatible with conveyor assemblies wherein either the pitch angle, the roll angle, or both, is variable. The weighing system includes a load cell that measures a force borne by the support member of the conveyor assembly. One or more clinometers are used to define the angular position of the conveyor assembly. The number of clinometers is great enough to fully define the pitch angle, the roll angle, and the direction through which the measured force acts. The measured angles, the measured force, and a tare weight of the conveyor are used to calculate the weight of the material. The weighing system may be adapted to measure a flow rate of the material. Furthermore, the conveyor assembly may be mounted on harvesting equipment in order to measure crop yield data and to generate maps depicting the crop yield distribution over a field.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.09/060,528, entitled "System For Weighing Material on a Conveyor," filedApr. 15, 1998, now U.S. Pat. No. 5,959,257 which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to weighing systems for measuring theweight of a material carried on a conveyor. In particular, the presentinvention relates to systems for weighing material carried on a conveyorassembly, wherein the one or both of the pitch angle and the roll angleof the conveyor assembly is variable relative to the horizontal plane.

2. The Prior State of the Art

Conveyors are widely used in industry in order to transport materialfrom one location to another. Conveyors are often used to transportmaterial in manufacturing, construction, and agricultural applications,to name just a few. There are a wide variety of conveyors, includingcontinuous belt devices that carry material and augers that movematerial using the rotary action of a helical member. Frequently,conveyors are used in processes wherein it is desirable not only to movethe material but also to measure the weight of the material.

Over the years, a number of systems for measuring the weight of conveyedmaterial have been developed. One approach involves discharging materialfrom a conveyor onto a scale, whereby the weight of the material ismeasured. Frequently, it is inconvenient to discharge material onto ascale, since conveyors are often used to make material available at adesired location for uses that are incompatible with the scale. Anothermethod involves positioning the entire conveyor assembly on the platformof a scale in order to measure the combined weight of the conveyorassembly and the material carried thereon. The tare weight of theconveyor assembly is subtracted from the combined weight measurement todetermine the weight of the material. This method may significantlyrestrict the environments in which conveyor assemblies may be used,since the platform of the scale is cumbersome and prevents easytransport of the conveyor assembly. The size and cost of the equipmentrequired in the foregoing methods further limit their practicability.

There have been developed further weighing systems which overcome someof the problems associated with the foregoing methods. For example, onesystem is based on the observation that the power required to operate aconveyor assembly is related to the weight of the material carried bythe conveyor. Accordingly, the system involves monitoring the powerconsumption of the conveyor assembly and calculating the weight of thematerial from the measured data. In addition, there are systems thatweigh material by using load cells under the conveyor belt or in thesupport member of the conveyor assembly.

Depending on the configuration of the conveyor assembly and theenvironment in which it is used, the systems that employ powerconsumption monitoring or load cells may adequately weigh the conveyedmaterial without significantly interfering with the operation of theconveyor assembly. However, the foregoing systems generally are notsuitable for measuring the weight of material on a conveyor having avariable pitch angle. For example, the power required to transportmaterial is a function of the vertical distance through which thematerial is moved. Varying the pitch of a conveyor changes the powerrequirements of the conveyor assembly. Consequently, the powerconsumption of such a conveyor assembly does not uniquely correspond tothe weight of the material. The method of monitoring power consumptionhas also been found to be limited to conveyors having a relativelyshallow pitch, in a range from about five degrees above the horizontalto about five degrees below the horizontal. Likewise, the forcemeasurements made by load cells in support members or under conveyorbelts change as the pitch of the conveyor assembly changes. Accordingly,load cells have generally been useful only in conveyors that have afixed pitch.

One approach for overcoming the problems of measuring weight on aconveyor having a variable pitch is presented in U.S. Pat. No. 4,788,930to Matteau. The pitch of the conveyors taught by Matteau is variable inthe sense that the angle between the centerline of the conveyor and thehorizontal plane may be changed as desired. Accordingly, conveyors thatare compatible with the weighing system of Matteau may have as many asone degree of rotational freedom relative to the horizontal plane.Matteau discloses using a clinometer in combination with a plurality offorce sensors that detect the load on a segment of a conveyor belt. Theclinometer provides information relating to the pitch of the conveyor,by which the force measurements from the force sensors may be adjustedin order to calculate the weight of the material.

The measurement system of Matteau, while overcoming some of the problemspreviously associated with measuring weight on a conveyor, has severaldrawbacks and limitations. For example, the system requires multiplesensors to be positioned under the conveyor belt, thereby increasing thecomplexity of the conveyor assembly. Moreover, Matteau extends toconveyors having at most one degree of rotational freedom relative tothe horizontal plane. An example of such a conveyor assembly is one thatis pivotally attached to a fixed base, such as a floor, and that may bepivotally raised and lowered by adjustment of a support member.Furthermore, many types of conveying chains and belts do not lendthemselves to having weighing sensors positioned thereunder, regardlessof the pitch of the conveyor.

There are a large number of conveyor assembly applications with whichthe existing weighing systems simply are not compatible. For example,conveyors are often transportable, and may be carried on a truck,harvesting equipment, or another vehicle. In such situations, it iscommon for the conveyor to be rotated relative to the horizontal planewith two degrees of freedom. In other words, both the pitch angle andthe roll angle of such conveyors are freely variable.

Often such conveyors may be further varied by adjusting the supportmember. Thus, the pitch angle of such conveyors may change according totwo mechanisms: unavoidable movement of the transporting vehicle andintentional adjustment of the support member. It can be understood thatthe angle of inclination with respect to the horizontal plane of suchadjustable support members is only partially dependent on the pitchangle. Accordingly, a third independent variable, in addition to thepitch angle and the roll angle, is introduced into some conveyor/supportmember assemblies.

Examples of conveyor assembles that have variable pitch angles and rollangles are common in agricultural settings wherein crops are harvestedusing a harvesting vehicle equipped with a conveyor. There are also manyother examples, including manufacturing and construction equipment foruse with gravel, cement, other bulk materials, and the like.Conventional conveyor assemblies and previously existing weighingsystems have not been able to accurately measure the weight of materialcarried on such variable-attitude conveyor assembles. Instead, costlyand inconvenient alternatives have been used, such as weighing thematerial before or after being conveyed. Occasionally, the onlyavailable system has been to make unreliable estimates of the weight ofthe material flowing on the conveyor.

It can be understood that there is a need in the art for systems forweighing material carried by a conveyor having a variable pitch whileavoiding the use of multiple load sensors as has been previouslypracticed. It would also be an advancement in the art to provideweighing systems that may be used with conveyor assemblies having morethan one degree of rotational freedom relative to the horizontal plane,such as those that have variable pitch angles and roll angles. It wouldbe particularly desirable to provide such weighing systems that couldalso be used with conveyors that are transported by trucks, harvestingequipment, or other vehicles.

SUMMARY AND OBJECTS OF THE INVENTION

The present invention relates to weighing systems for measuring theweight of material carried on a conveyor. The weighing systems may beused with conveyors having a variable pitch angle, regardless of whetherthe pitch angle may be varied as a result of adjustment of a supportmember, transport of the conveyor over uneven terrain, or both.Moreover, the weighing systems are compatible with conveyors that haveboth a variable pitch angle and a variable roll angle.

The angular position of the conveyor assembly is measured by one or moreclinometers. In embodiments of conveyor assemblies wherein the pitchangle is variable and the roll angle is substantially fixed, oneclinometer is used to provide data that specifies the pitch angle. Whenboth the pitch angle and the roll angle are variable, the weighingsystem includes two clinometers that provide data used to specify boththe pitch angle and the roll angle.

As few as one load cell may be used to detect the forces borne by theconveyor assembly. The load cell may be integrally positioned in asupport member that bears part of the weight of both the conveyor andthe material carried thereon. In an embodiment of the invention, anadditional clinometer is included in the weighing system in order tospecify the direction through which the measured force acts. Preferably,this clinometer is positioned in relation to the support member so as tomeasure the support member's angle of inclination with respect to thehorizontal plane.

In general, the weighing systems include a number of clinometers that issufficient to specify the pitch angle and the roll angle of the conveyorand the angle of inclination of the support member. The minimum numberof clinometers required depends on the mechanical relationship betweenthe support member and the conveyor and the mechanical relationshipbetween the entire conveyor/support member assembly and the horizontalplane.

One embodiment of the methods for using the weighing systems of theinvention involves first providing a conveyor assembly and disposingmaterial thereon. The material may be continually transported by theconveyor and the total weight of the material on the conveyor maycontinually change during the weighing procedure. Furthermore, theangular configuration of the conveyor assembly may be continuously orrepeatedly varied during the weighing operation.

The method further includes detecting a load in the support member ofthe conveyor assembly using the load cell. The clinometers also providethe data used to specify the pitch angle and the roll angle of theconveyor and the angle of inclination of the support member. A pluralityof low pass, anti-aliasing filters may be used, one per channel, tofilter the analog signals generated by the load cell and theclinometers, after which the signals are processed by ananalog-to-digital converter.

The resulting digital signals are transmitted to a processor. Theprocessor also accesses other relevant information, which may includedata relating to the dimensions of the conveyor assembly and apreviously-measured tare weight of the conveyor. Using the foregoingmeasurements and known data and, assuming the material is uniformlydistributed on the conveyor, the processor calculates the weight of thematerial. If a flow rate of the material is desired, the weighing systemfurther includes a shaft speed sensor attached to a pulley of theconveyor.

The weighing process may be repeated as desired as time progresses, suchthat variations in the weight of the material may be monitored. Theweight measurements may be stored for future reference or may be used inany other desired manner. According to one application for the weighingsystems of the invention, weight measurements are taken during a cropharvesting operation. For example, a conveyor assembly may be mounted onharvesting equipment such that the harvested crops are placed on theconveyor. The weighing system may be thereby used to determine theweight of the harvested crops. Furthermore, the yield and the yielddistribution of the crops may be calculated, and the yield variations ofthe crops may be mapped using a global positioning system in combinationwith the weighing system.

In view of the foregoing, it can be appreciated that the weighingsystems of the invention allow material carried on a variable pitchconveyor to be weighed using only one load sensor. The use of multipleclinometers allows the weight of material carried by a conveyor havingboth a variable pitch angle and a variable roll angle to be calculated.Moreover, the weighing systems are compatible with conveyor assembliesthat are transported by trucks, harvesting equipment, or other vehicles.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the elements, steps, and combinations particularly pointed outin the appended claims. These and other objects and features of thepresent invention will become more fully apparent from the followingdescription and appended claims, or may be learned by the practice ofthe invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained, a more particular descriptionof the invention briefly described above will be rendered by referenceto specific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1A-1C are elevation views of examples of conveyor assemblies thatmay be used with the weighing systems of the invention.

FIG. 2 illustrates an example of an environment in which conveyorassemblies and weighing systems of the invention may be used.

FIG. 3A is an elevation view of the conveyor assembly of FIG. 1A,further depicting selected elements of the weighing system andillustrating a variable pitch angle of the conveyor assembly.

FIG. 3B is an end view of a the conveyor assembly of FIG. 3A,illustrating a variable roll angle of the conveyor assembly.

FIG. 4 illustrates selected known and unknown quantities and dimensionsthat may be used according to one embodiment of the invention forcalculating the weight of the material carried on the conveyor.

FIG. 5 is a block diagram illustrating one example of the operation ofthe weighing systems of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to weighing systems for measuring theweight of material carried on a conveyor. The weighing systems may beused with conveyors having a variable pitch angle, regardless of whetherthe pitch angle may be varied as a result of adjustment of a supportmember, transport of the conveyor over uneven terrain, or both.Moreover, the weighing systems are compatible with conveyors that haveboth a variable pitch angle and a variable roll angle.

The weighing operation may be conducted using as few as one load cellintegrally positioned on a support member of the conveyor assembly. Theweighing system compensates for any variable component of the angularposition of the conveyor/support member assembly by using clinometers orother angular position sensors. In general, enough clinometers are usedin order to specify the pitch angle and the roll angle of the conveyorand the support member's angle of inclination with respect to thehorizontal plane. When one or more of the pitch angle, the roll angle,and the angle of inclination of the support member is fixed or isentirely dependent on one of the other angles, the minimum number ofclinometers may be correspondingly reduced. Once the pitch angle, theroll angle, and the angle of inclination of the support member have beenmeasured or otherwise defined, the force measured by the load cell maybe used to calculate the weight of the material on the conveyor.

As used herein, the terms "pitch" and "pitch angle" refer to the angulardisplacement or slope of the centerline of a conveyor from thehorizontal plane. The pitch angle is measured about a "pitch axis",which is perpendicular to the centerline of the conveyor and parallel tothe horizontal plane. The terms "roll" and "roll angle", as used herein,refer to the angular displacement between the conveyor and thehorizontal plane measured about a "roll axis" perpendicular to the pitchaxis and parallel to the horizontal plane. Accordingly, the pitch angleand the roll angle of the conveyors are measured about mutuallyperpendicular axes, each of which is parallel to the horizontal plane.

The pitch angle and the roll angle of a conveyor together uniquelydefine the "attitude" of the conveyor. The "attitude" of a conveyorrefers to the angular position or orientation of the conveyor withrespect to the horizontal plane. The yaw, or the rotation about thevertical axis, is generally ignored in describing the position of theconveyors, since the yaw generally does not affect the operation of theweighing systems of the invention. As used herein, the "angle ofinclination" of a support member refers to the angle between thelongitudinal axis of the support member and the horizontal plane.

Any desired mechanism may be responsible for changing the angularposition of the conveyor assemblies relative to the horizontal plane.For example, in some conveyor assemblies, the pitch angle of conveyormay be intentionally raised or lowered by adjusting a support member.Such adjustment of the conveyor results in a conveyor having one degreeof rotational freedom relative to the horizontal plane. Other conveyorassemblies may be transported by a vehicle with the result that theentire conveyor assembly rotates according to two degrees of freedomrelative to the horizontal plane as the vehicle traverses uneventerrain. Many of the conveyor assemblies that are transported byvehicles further may be intentionally raised and lowered by adjustingthe support member such that three independent variables are introducedinto the angular position of the conveyor/support member assemblies. Inparticular, such conveyor/support member assemblies may have variablepitch angles, variable roll angles, and variable angles of inclinationof the support members. The conveyor assemblies that may be used withthe weighing systems of the invention are not limited to those describedabove, and may instead have other mechanical relationships between theconveyor, the support member, and the horizontal plane.

The invention is described herein by making primary reference to anembodiment wherein each of the pitch angle, the roll angle, and theangle of inclination of the support member may vary independently.However, it is to be understood that the disclosed examples arepresented for illustration purposes, and that the principles taughtherein may be applied to weighing systems that are compatible with otherconveyor assemblies. Furthermore, the weighing systems can be installedon new conveyor assemblies, while existing conveyor assemblies may beretrofitted with weighing systems as well.

FIG. 1A illustrates one conveyor assembly that may be used with theweighing systems of the invention. Conveyor assembly 10 includes aconveyor 12 and a support member 14 in a pivotal relationship with theconveyor. Conveyor 12 is pivotally attached to a base 16 at a first end18 and is further connected to support member 14 at a second end 20. Thepivotal connection at first end 18 may be accomplished by means of a pinpassing through the first end. Conveyor 12 may be selectively raised andlowered as indicated at reference number 19 by adjusting the effectivelength of support member 14 using a hydraulic ram 22. Support member 14,as illustrated in FIG. 1A, is a cable or chain that bears a tensileforce.

The conveyors used with the weighing systems of the invention may be anystructure for carrying, pushing, or otherwise transporting or guidingmaterial from along the structure. For example, conveyor 12 in FIG. 1Ais an endless belt-type conveyor having a belt 24 that is moved by afirst pulley 26 and a second pulley 28. Such conveyors are well known inthe art. Alternatively, belt 16 may be a drag-chain for carryingmaterial. Another example of a conveyor that may be used with theweighing systems of the invention is an auger assembly that pushesmaterial by rotation of a helical member.

FIG. 1B is an alternative example of a conveyor assembly that may beused with the invention. Conveyor assembly 30 includes a conveyor 12 anda telescoping support member 32 that supports the conveyor under acompressive force. Conveyor 12 may be raised or lowered by adjusting theeffective length of support member 32. Likewise, conveyor assembly 40 ofFIG. 1C is a further example of a conveyor assembly that may be usedwith the invention, and also has a conveyor 12 connected to a supportmember 32. It should be understood that the invention is not limited tothe conveyor assemblies of FIGS. 1A-1C, and that a wide variety of otherconveyor assemblies may be used in conjunction with the weighing systemsof the invention.

The conveyor assemblies illustrated in FIGS. 1A-1C are configured suchthat the pitch angle may be varied by selectively adjusting the supportmember. Likewise, the support members' angle of inclination with respectto the horizontal plane is variable in conveyor assemblies 10, 30, and40.

As illustrated in FIG. 2, the conveyor assemblies for use with theinvention may be transported on a vehicle so that the pitch angle andthe roll angle are variable. FIG. 2 presents one example of anenvironment in which conveyor assemblies and associated weighing systemsmay be used. In particular, conveyor assembly 10 is mounted onharvesting equipment 34 for use during a harvesting operation.Harvesting equipment 34 is one example of harvesting means for gatheringcrops and disposing the crops on the conveyor assembly. It has beenfound that conveyor assembly 10 may be advantageously used to harvestear corn, for example. Furthermore, conveyor assembly 30 of FIG. 1B maybe advantageously used to harvest grapes.

Harvesting equipment 34 gathers crops growing within a swath having awidth, W, as the harvesting equipment is driven across a field, and thecrops 36 are disposed on conveyor 12. As seen in FIG. 2, harvestingequipment optionally includes a global positioning system receiver 38,and a conventional vehicle speed sensor (not shown) the purpose of whichis discussed in greater detail below. During the harvesting operation,harvesting equipment 34 typically encounters uneven terrain, with theresult that the pitch angle and the roll angle of conveyor 12 repeatedlychange. Accordingly, conveyor 12 has two degrees of rotational freedomwith respect to the horizontal plane. Moreover, the angle of inclinationof support member 14 is not completely dependent on the attitude ofconveyor 12, since the pitch angle of the conveyor may vary as a resultof the action of the support member, the uneven terrain encountered bythe harvesting equipment, or both.

FIGS. 3A and 3B further illustrate the rotational motion experienced byconveyor assembly 10 and the weighing system used to calculate theweight of the material carried thereon. FIGS. 3A and 3B include twocoordinate reference frames by which the rotational motion of theconveyor assemblies may be understood. The XYZ reference frame isdefined herein to be fixed with respect to the horizontal plane.Accordingly, both the X axis and the Y axis are horizontal and the Zaxis is vertical. In contrast, the X'Y'Z' reference frame is defined tobe fixed with respect to the conveyor assembly. In other words, rotationof the conveyor assembly is accompanied by corresponding rotation of theX'Y'Z' reference frame.

Conveyor assembly 10 of FIG. 3A has undergone rotation whereby the X'axis has been displaced from the X axis. This motion has the effect ofchanging the pitch angle, of conveyor 12, since is measured with respectto the horizontal plane. Moreover, FIG. 3B illustrates rotation ofconveyor assembly 10 in which the roll angle of conveyor 12 has beenchanged. It is also noted that the "pitch axis" about which the pitchangle has been measured in FIG. 3A is parallel to the Z axis and thatthe "roll axis" about which the roll angle has been measured in FIG. 3Bis parallel to the X axis.

The XYZ and X'Y'Z' reference frames are presented herein as but one ofmany possible manners of describing the relative motion of the elementsof the conveyor assemblies of the invention. Thus, the foregoingreference frames are not intended to limit the scope of the invention,which could be equally well described according to other referenceframes.

The weighing system for use with conveyor assembly 10 includes a loadcell 42 positioned in support member 14 in order to detect the forceborne by the support member. Load cell 42 may be any suitable device fordetecting a load and outputting an electrical signal that corresponds tothe detected load, and is therefore one example of means for sensing aforce borne by the support member. One example of the many suitable loadcells that may be used with the invention is load cell model #RSCmanufactured by HBM, Inc., of Framingham, Mass. Load cell 42 may bepositioned at support member 14 at any location where the force borne bythe support member may be measured. For example, load cell 42 may bedisposed at some point in the length of support member 14 as shown inFIG. 1A, or instead may be located at one of the ends of the supportmember. The weighing system may also include an overload protectionsystem, whereby the load cell is prevented from sensing extreme forcesthat may be experienced during the dynamic movement of the conveyorassembly.

The load cell may be aligned with the longitudinal axis of the supportmember in order to measure a force acting in a direction parallel to thesupport member. Such an alignment of load cell 42 is illustrated in FIG.3A. However, the load cell may instead be aligned in other selecteddirections so as to detect a force acting in a direction that isnon-parallel to the support member. For example, a force sensor may bepositioned at the junction between the support member and the conveyorso as to measure a force in a direction tangent to the rotational pathof the conveyor instead of the direction parallel to support member. Aload cell, whether it is aligned in a direction parallel or non-parallelwith the longitudinal axis of the support member, is expressly intendedto correspond to the means for sensing a force borne by the supportmember.

In the alternative, hydraulic ram 22 of FIG. 1A or support members 32 ofFIG. 1B and 1C may include a force-detecting device incorporated withina hydraulic or pneumatic piston. Any force detecting device thatfunctions in conjunction with a hydraulic or pneumatic piston is afurther example of means for sensing the force borne by the supportmember.

This embodiment of the weighing system further includes means formeasuring the attitude of the conveyor. In the embodiment of theinvention illustrated in FIG. 3A, such means includes a clinometer 44positioned in relation to conveyor 12 so as to detect the pitch angle ofthe conveyor. Clinometer 44 and other clinometers disclosed herein maybe any device for generating an electrical signal in response to theangular position of the device. One example of the many clinometers thatmay be advantageously used with the invention is clinometer model#AWI1101 manufactured by APTEK Williams, Inc., of Deerfield Beach, Fla.The means for measuring the attitude of the conveyor in the embodimentillustrated in FIG. 3A further includes a clinometer 46 positioned inrelation to conveyor 12 so as to detect the roll angle of the conveyor.

Conventional clinometers detect changes in an angular position as theclinometers are caused to rotate about their measurement axis. In FIG.3A, the measurement axis of clinometer 44 extends out of the page and isparallel to the pivotal axis of conveyor 12 (the axis passing throughfirst end 18 about which the conveyor pivots). Furthermore, themeasurement axis of clinometer 46 is shown as being parallel tocenterline 48 of conveyor 12. The foregoing alignment of the clinometersis one convenient configuration selected from a great number of possibleconfigurations of the clinometers. It can be understood that the outputof two clinometers having any of a large number of measurement axes canbe used to specify the attitude of a conveyor, subject to the followinglimitations. First, the measurement axes of the two clinometersgenerally should be mutually non-parallel so as not to merely duplicatethe measured data. Second, as the direction of a measurement axis of aclinometer approaches verticality, the clinometer begins to providefaulty data.

Accordingly, the weighing systems of the invention may includeclinometers 44 and 46 with their measurement axes in substantially anydirection, subject to the foregoing limitations. Of course, depending onthe configuration of the measurement axes of the clinometers, the outputof the clinometers may need to be processed according to thetrigonometric methods or otherwise adjusted in order to define theattitude of the conveyor. In summary, any combination of clinometersthat provides data that may be used to uniquely define the attitude ofthe conveyor are suitable examples of the means for measuring theattitude of the conveyor and may be used according to the invention.

The weighing system further includes means for measuring the directionthrough which the force borne by the support member acts. One example ofsuch means is a clinometer 52 positioned with respect to support member14 so as to detect the angle of inclination. Clinometer 52 may besimilar to clinometers 44 and 46 disclosed herein. Clinometer 52 asdepicted in FIG. 3A has a measurement axis parallel to the measurementaxis of clinometer 44. However, the measurement axis of clinometer 52may have any other alignment that permits clinometer 52 to generate datathat may be used to uniquely specify the angle of inclination of supportmember 14. As but one example of the other possible alignments, themeasurement axis could be rotated several degrees in any selecteddirection from the alignment shown in FIG. 3A, while still providingdata that may be used to specify the angle of inclination. Again,depending on the alignment of the measurement axis of clinometer 52, theoutput of the clinometer may need to be adjusted according totrigonometric methods in order to define.

An alternative structure that corresponds to the means for measuring thedirection of the force is a length transducer optionally integrated insupport member 14. For example, hydraulic ram 22 may include atransducer that provides data that may be used to specify the length ofsupport member 14. The measured length of support member 14 may becombined with fixed dimensions of the conveyor assembly in order toidentify the length of the three legs of a triangle (i.e., supportmember 14, conveyor 12, and the distance between base 17 and base 18).Accordingly, the attitude of conveyor 12 and the measured length ofsupport member 14 may be used to identify the value of.

As mentioned previously, the load cell may be optionally aligned tomeasure a force that acts in a direction that is not parallel with thelongitudinal axis of the support member. In such situations, clinometer52 may be positioned on the conveyor assembly so as to measure thedirection of the force, instead of measuring the angle of inclination ofthe support member. Furthermore, in some conveyor assemblies, thedirection of the force may be dependent on the attitude of conveyor 12instead of on the angle of inclination of support member 14. In suchcircumstances, clinometer 52 may be eliminated entirely, since thedirection of the measured force may be defined by specifying theattitude of the conveyor using clinometers 44 and 46. In this case,clinometers 44 and 46 may correspond to the means for measuring thedirection through which the force acts.

If the weighing system is to be used to provide flow rate measurementsin addition to, or in place of, weight measurements, the weighing systemfurther includes means for determining the speed of the conveyor.According to one embodiment of the invention, the means for determiningthe speed of the conveyor includes a conventional shaft rotation sensor50 attached to pulley 26 or, in the alternative, to pulley 28 so as tomonitor the rate of rotation of the pulley, which is easily translatedinto the conveyor speed. It may be preferable to attach shaft speedsensor 50 to the non-powered pulley to eliminate error that mightotherwise be introduced by drive wheel slippage. Typically, thenon-powered pulley is pulley 26.

FIG. 4 illustrates selected dimensions of the conveyor assembly that maybe used in one set of equations for calculating the weight of thematerial on the conveyor. For purposes of clarity, the systemillustrated in FIG. 4 is two-dimensional, and depicts the forces anddimensions having been already adjusted for any variations in the rollangle of the conveyor. The unknown quantities in FIG. 4 are the weightof the material, F_(m), and the forces F_(x) and F_(y) that act on thepin at first end 18 of conveyor 12. The three unknown quantities may bedetermined using three static force equations in the two-dimensionalsystem of FIG. 4: summation of forces in the X direction, summation offorces in the Y direction, and summation of moments about first end 18.In practice, since F_(x) and F_(y) act through first end 18, F_(m) isthe only unknown quantity in an equation wherein moments are summedabout first end 18. Thus, the summation of moments about first end 18 issufficient to identify the weight of the material according to thisembodiment of the invention.

The values that are used in summing the moments about first end 18 aredepicted in FIG. 4 and are described as follows. The measured force,F_(S), is measured by the load cell and acts through a direction definedby, which is measured according to the methods disclosed herein. Thetare weight of the conveyor, F_(c), is a measured value, and isgenerally constant throughout the weighing operation. The tare weightF_(c) may be identified by any desired method, examples of which aredisclosed in greater detail below. The distances between first end 18and the points through which the forces F_(m), F_(s), and F_(c) act arerepresented by D_(m), D_(s), and D_(c), respectively in FIG. 4.Distances D_(c) and D_(s) are predetermined and fixed, while distanceD_(m) is determined by assuming a constant position of the center ofmass of the material carried on the conveyor.

As shown in FIG. 4, depending on the configuration of the elements ofthe conveyor assembly, the angular positions of D_(m), D_(s), and D_(c),may be offset by a fixed amount from the pitch angle,, which may bemeasured according to the methods disclosed herein. For example, theassumed center of mass of the material on the conveyor may displacedfrom through a small offset angle with respect to first end 18. Thisoffset angle of the center of mass of the material is shown at m.Likewise, there may be offset angles _(s) and _(c) that correspond toforces F_(s) and F_(c), respectively.

In light of the disclosure made herein, those skilled in the art willunderstand the computational methods used for calculating the weight ofmaterial 36 using the data generated by load cell 42 and clinometers 44,46, and 52. Trigonometric methods may be used to resolve the forces anddimensions into directional components that may be conveniently used inthe static force equations and algorithms. The specific equations,algorithms, and measured and fixed values depend, of course, on thespecific configuration of the conveyor assembly with which the weighingsystem is used.

The weighing system has been described in reference to FIGS. 3A and 3B,which depict a conveyor assembly mounted on harvesting equipment oranother supporting structure such that the conveyor has a variable pitchangle and a variable roll angle and the support member has a variableangle. Accordingly, the angular position of the elements of theconveyor/support member assembly has three independent variables. Theinvention extends, however, to conveyor assemblies having fewer variableangular measurements. For example, some conveyor assemblies may have afixed roll angle and a variable pitch angle. Consequently, clinometer 44may be used without clinometer 46 to measure the attitude of theconveyor, in which case, the means for measuring the attitude of theconveyor could include only one clinometer.

In view of the foregoing, it is to be understood that the inventionextends to weighing systems for use with conveyor assemblies having anycombination of variable or fixed pitch angles, roll angles, and anglesof inclination of the support members. Moreover, the weighing systemsmay be used with any such conveyor assembly, whether or not the angularpositions of the elements of the conveyor assembly are actually beingadjusted.

FIG. 5 is a schematic diagram illustrating the flow and processing ofinformation in a representative embodiment of a weighing system for usewith a conveyor assembly mounted on a vehicle. Clinometers 44, 46, and52 generate analog electrical signals 54 corresponding to the angularposition of the elements of the conveyor assembly according to themethods disclosed herein. Load cell 42 also generates data in the formof an analog electrical signal 56 representing the force borne by thesupport member. In some environments in which the weighing systems ofthe invention are used, the weighing systems experience vibration, withthe result that the signals 54 and 56 include noise. Much of the noisecan be reduced by passing signals 54 and 56 through a conventional lowpass anti-aliasing filter 58.

The filtered signals are sent to an analog-to-digital converter 60 togenerate digital signals compatible with digital processor 62. If theweighing system is to be used to calculate the flow rate of the materialon the conveyor, shaft speed sensor 50 transmits signals toanalog-to-digital converter 60. Furthermore, if the weighing system isused, for example, with harvesting equipment 34 of FIG. 2, a vehiclespeed sensor 64 is optionally included to generate signals formonitoring the motion of the harvesting equipment across a field.

The measured data is transmitted to processor 62, which may be anysuitable digital processing device having circuitry and/or executablecode for executing the algorithms used to determine the weight of thematerial from the measured and known data. By way of example, onesuitable processor 62 is model #HM-500 manufactured by HarvestMaster,Inc., of Logan, Utah. Thus, processor 62 is but one example of digitalprocessor means for calculating the weight of the material using datarepresenting the measured force, the measured direction of the force,and the measured attitude of the conveyor.

Known data storage 66 stores fixed, known, or already-measured data thatis used by processor 62 in calculating the weight of the material, theflow rate of the material, the yield distribution of crops, or the like.Known data storage 66 may be any suitable device for storingcomputer-readable data, and may be integrated with processor 62.Examples of the data that may be contained in known data storage 66include the pre-determined or fixed values described above in referenceto FIG. 4 and any other desired fixed dimension or physical property ofthe elements of the conveyor assembly.

Processor 62 may be used to calculate any desired metric, such as theweight, flow rate, crop yield, yield distribution, etc., of the materialdisposed on the conveyor assembly. In one embodiment of the invention,the weight of the material is calculated by taking a running average ofa set of discrete samples over a period of time. By way of example, andnot by limitation, the low pass filter 58 may have a threshold value ofabout 3 Hz, the signals may be sampled by the processor at a rate of 6Hz or greater, and the running average may be calculated over a periodof about 2 seconds. Of course, the desired filter, sample rate, andrunning average period may be highly dependent upon the particularapplication with which the weighing system is used.

In general, the algorithms executed in processor 62 for calculating theweight of the material, the flow rate, and the like, depend directly orindirectly on a measured value for the weight of the conveyor.Accordingly, a value of the tare weight of the conveyor is contained inknown data storage 66 and is sent to processor 62 when needed. The tareweight may be obtained by any desired method. Typically, the tare weightis identified by conducting a weighing operation according to themethods disclosed herein in the absence of material on the conveyor. Thetare weight of the conveyor is then stored in known data storage 66 soas to be available during subsequent weighing operations of materialpositioned on the conveyor.

The weighing system and processor 62 can be used to calculate the flowrate of the material on the conveyor by identifying the running averageof the weight of the material, the conveyor speed from shaft speedsensor 50, and a fixed residency length of the material on the conveyor.The residency length of the material is the distance through which thematerial is carried while on the conveyor.

When the weighing system is used with harvesting equipment, the yield,the yield distribution, and the total weight of the harvested crops maybe calculated as desired. The yield of harvested crops is conventionallyexpressed in unit weight per unit area. The weight may be calculatedaccording to the methods disclosed herein. The area from which the cropsare harvested may be identified, for example, by combining the output ofa vehicle speed sensor 64 with a fixed or variable width, W, of theswath from which harvesting equipment 34 harvests crops as shown in FIG.2.

The yield distribution of the crops over the harvested field maycalculated by combining the yield data with information generated bypositional locating means for detecting the position of the weighingsystem and the associated equipment on the field or tract of land. Oneexample of such positional locating means is a global positioning system(GPS) receiver 38 as shown in FIG. 2. The function of a globalpositioning system for determining the position of a moving object iswell known by those skilled in the art. In the alternative, any otherconventional device or system for specifying the variable position of amoving object may constitute the positional locating means. Thepositional data of GPS receiver 38 may be passed to processor 62 andcorrelated with the calculated yield data, in order to identify cropyields associated with specific regions of the field.

The process of calculating the weight of the material on the conveyorand/or identifying any of the other desired measurements may berepeatedly conducted over time as the weight of the material and theangular position of the conveyor assembly change. It is noted that theweighing system either implicitly or explicitly calculates a weight ofthe material in the process of calculating the other measurements suchas flow rate, yield, yield distribution, etc. Thus, regardless of theparticular property of the material identified using systems of theinvention, processor 62 is an example of digital processor means forcalculating the weight of the material.

As the processor calculates each value of the weight of the material,the yield of the crops, the position of the conveyor assembly, etc., thecalculated value may then be directed to data storage 68, which is anysuitable device for storing computer-generated data Furthermore, datastorage 68 may be a memory device integrated with processor 62. Duringthe processes of calculating the desired measurement and displaying themeasured values to a user, the information stored in data storage 68 maybe retrieved as desired.

The weighing system preferably includes a user interface 70 thatdisplays the weight or other values calculated by processor 62 and/orallows the user to select sensor settings or access weighing systemdiagnostics. For example, user interface 70 may include an operatorconsole, a computer display screen or another graphical display unit fordisplaying instantaneous or average material weight measurements or cropyields. When the weighing system is used in a harvesting operation, userinterface 70 may display a running total of the weight of the cropsharvested or conveyed to truck 72 illustrated in FIG. 2.

In one embodiment of the invention, the weighing system is used togenerate a map of the yield and the distribution of the yield over aharvested field. For example, the processor 62 associates the yield datawith the positional data gathered by global positioning system receiver38. The yield data and the positional data may be displayed to the userthrough the user interface 70 by means of a computer display screen.Alternatively, a printed copy of the map may be produced by userinterface 70. Thus, the combination of processor 62 and user interface70 is one example of mapping means for visually representing the cropyield with respect to the location on the field from which the cropshave been harvested.

The manner in which the data is processed and displayed to the user isnot limited to the examples described herein. The data may be displayedto the user in any other form, and the weight data may be processed asdesired. The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A system for measuring the weight of a material during aprocess of conveying said material, said system comprising:a conveyorassembly including:a conveyor having an attitude defined by a pitchangle and a roll angle, wherein at least one of said pitch angle andsaid roll angle is variable; and a support member pivotally connected tosaid conveyor; means for sensing a force borne by said support member;means for measuring a direction through which said force acts; means formeasuring said attitude of said conveyor; and a processor forcalculating the weight of said material using data representing saidforce, said direction through which said force acts, and said attitudeof said conveyor.
 2. A system as defined in claim 1, wherein said meansfor sensing said force comprises a load cell integrally positioned insaid support member.
 3. A system as defined in claim 1, wherein saidmeans for sensing said force comprises only one load cell.
 4. A systemas defined in claim 1, wherein said means for sensing said forcecomprises a load cell in contact with one end of said support member. 5.A system as defined in claim 1, wherein said means for measuring saiddirection comprises a clinometer positioned in relation to said supportmember so as to detect an angle of inclination of said support member.6. A system as defined in claim 1, wherein said pitch angle is variableand said roll angle is substantially fixed, said means for measuringsaid attitude of said conveyor comprising a clinometer positioned inrelation to said conveyor so as to detect said pitch angle.
 7. A systemas defined in claim 1, wherein each of said pitch angle and said rollangle are variable, said means for measuring said attitude of saidconveyor comprising a first clinometer and a second clinometerpositioned in relation to said conveyor so as to detect said pitch angleand said roll angle.
 8. A system as defined in claim 1, wherein saidconveyor assembly is supported by a supporting structure such that saidpitch angle and said roll angle are variable and said support member hasan angle of inclination with respect to the horizontal plane that is atleast partially independent of said pitch angle, and wherein:said meansfor measuring said attitude of said conveyor comprises a firstclinometer and a second clinometer positioned in relation to saidconveyor so as to detect said pitch angle and said roll angle; and saidmeans for measuring said direction comprises a third clinometerpositioned in relation to said support member so as to detect said angleof inclination.
 9. A system as defined in claim 1, wherein said materialcomprises crops and wherein said system further comprises harvestingmeans for gathering said crops and disposing said crops on saidconveyor.
 10. A system as defined in claim 9, wherein said supportmember has a length that can be adjusted.
 11. A system as defined inclaim 10, wherein said support member and said conveyor are in amechanical relationship such that adjustment of the length of saidsupport member varies said pitch angle of said conveyor.
 12. A system asdefined in claim 1, further comprising positional locating means fordetecting a position of said system on a tract of land.
 13. A system asdefined in claim 11, wherein said positional locating means comprises aglobal positioning system receiver.
 14. A system as defined in claim 1,further comprising means for determining a speed of said conveyor.
 15. Asystem as defined in claim 1, wherein said support member supports saidconveyor rather than supporting only a portion of a belt of saidconveyor.
 16. A system for measuring the weight of a material during aprocess of conveying said material, said system comprising:a conveyorassembly including:a conveyor having an attitude defined by a pitchangle and a roll angle, wherein at least one of said pitch angle andsaid roll angle is variable; and a support member connected to saidconveyor and supporting said conveyor rather than supporting only aportion of a belt of said conveyor; means for sensing a force borne bysaid support member; means for measuring a direction through which saidforce acts; means for measuring said attitude of said conveyor; and aprocessor for calculating the weight of said material using datarepresenting said force, said direction through which said force acts,and said attitude of said conveyor.
 17. In a system for carrying amaterial on a conveyor assembly, wherein said conveyor assembly includesa conveyor having a variable attitude defined by a pitch angle and aroll angle, and wherein said conveyor assembly further includes asupport member connected to said conveyor, a method for measuring theweight of said material, comprising the steps of:adjusting a length ofsaid support member, such that said pitch angle of said conveyor isvaried; disposing said material on said conveyor assembly; measuring aforce borne by said support member; measuring a direction through whichsaid force acts; measuring said variable attitude of said conveyorassembly; and calculating said weight of said material using at leastsaid measured force, said measured direction, and said measured variableattitude.
 18. A method as defined in claim 17, wherein said step ofmeasuring said force comprises using only one load cell.
 19. A method asdefined in claim 17, wherein said pitch angle and said roll angle areeach variable, and wherein said step of measuring said variable attitudecomprises using a first clinometer and a second clinometer to detectsaid attitude.
 20. A method as defined in claim 17, wherein each of thesteps of measuring said force, measuring said direction through whichsaid force acts, and measuring said variable attitude comprises passingat least one signal through a low pass, anti-aliasing filter.
 21. Amethod as defined in claim 17, wherein said step of measuring saiddirection comprises using a clinometer positioned in relation to saidsupport member so as to detect an angle of inclination of said supportmember with respect to the horizontal plane.
 22. A method as defined inclaim 17, further comprising the step of calculating a flow rate of saidmaterial after said step of calculating said weight.
 23. A method asdefined in claim 17, wherein said material is crops and wherein saidmethod further comprises an ongoing step of harvesting said crops, saidpitch angle and said roll angle each varying during said step ofharvesting said crops.
 24. A method as defined in claim 23, wherein saidstep of calculating said weight is repeatedly conducted during said stepof harvesting said crops.
 25. A method as defined in claim 23, furthercomprising the step of repeatedly determining a variable position ofsaid system on a field.
 26. A method as defined in claim 25, furthercomprising the step of storing data representing said weight of saidcrops and said variable position of said system.
 27. A method as definedin claim 26, further comprising the steps of:measuring a rate at whichsaid conveyor assembly is carried over said field; measuring a conveyorspeed; and determining a width of a swath across said field from whichsaid crops are harvested.
 28. In a system for harvesting crops andconveying said crops using a harvesting vehicle equipped with a conveyorassembly, wherein said conveyor assembly includes a conveyor having avariable attitude, and wherein said conveyor assembly further includes asupport member connected to said conveyor, a method for mapping a yielddistribution of said crops over a field, comprising the steps of:causingsaid harvesting vehicle to traverse said field such that said crops areharvested and disposed on said conveyor; and repeating, as saidharvesting vehicle traverses said field, the steps of:measuring a forceborne by said support member; measuring a direction through which saidforce acts; measuring a variable attitude of said conveyor assemblyusing at least two clinometers, said variable attitude being defined bya variable pitch angle and a variable roll angle; calculating saidweight of said crops using at least said measured force, said measureddirection, and said measured variable attitude; detecting a position ofsaid harvesting vehicle on said field; and correlating said calculatedweight with said detected variable position.